Vapor deposition coating apparatus

ABSTRACT

The invention relates to a vapor deposition coating apparatus. More particularly it relates to an apparatus in which the ion current density is carefully controlled to improve coating. This control enhances the versatility and enlarges the range of deposition conditions which can be achieved within a single apparatus, so that coatings with very different properties can be deposited in the same equipment. The vapor deposition apparatus includes a vacuum chamber ( 1 ), at least one coating means or ionisation source ( 3 ) disposed at or about the periphery of a coating zone ( 2 ), one or more internal magnetic means ( 6 ) positioned such that the magnetic field lines ( 7 ) are generated across the coating zone ( 2 ) and means for altering the strength or position of the magnetic field lines to aid confinement.

TECHNICAL FIELD

[0001] This invention relates to a vapour deposition coating apparatus.More particularly it relates to an apparatus in which the ion currentdensity is carefully controlled to improve coating. This controlenhances the versatility and enlarges the range of deposition conditionswhich can be achieved within a single apparatus, so that coatings withvery different properties can be deposited in the same equipment. Also,the present invention enables high quality coatings to be deposited in alarge volume apparatus improving the coating productivity and componentthroughput. The deposition apparatus is based upon magnetron sputteringsources in which the ion current driven towards the samples is carefullycontrolled.

BACKGROUND ART

[0002] Magnetron sputtering is a very well established technique whichis able to produce high quality vapour deposited coatings for a widerange of applications.

[0003] A number of improvements in magnetron sputtering have occurredduring the last ten years. The first break through was provided by theunbalanced magnetron [B. WINDOWS, N. SAVVIDES, J. Vac. Sci. Technol., A4(1986) 453] which improved the ion flux escaping the magnetronsurrounding so the samples to be coated were subjected to a higher ionbombardment with beneficial effects in the structure of certain types ofcoatings. Variations in this principle and control modes for the degreeof unbalancing have been previously disclosed [W. MAASS, B. CORD, D.FERENBACH, T. MARTENS, P. WIRZ, Patent DE 3812379 Apr. 14, 1988].

[0004] In the case of large volume coating apparatus it has beennecessary to provide high ionisation sources in areas well away from themagnetron. This extra ionisation has been implemented by the use ofsupplementary excitation sources such as radio-frequency and microwavemeans [M. NIHEI, J. ONUKI, Y. KOUBUCHI, K. MIYAZAKI, T. ITAGAKI, PatentJP 60421/87 Priority Mar. 16, 1988] and the provision of magneticarrangements next to the magnetron sources [D. G. TEER, Proceedings forthe First International Symposium on Sputtering and PlasmaProcessing—ISSP∘91,Tokyo, Japan, February 1991; and A.FEUERSTEIN, D.HOFMANN, H. SCHUSSLER, Patent DE 4038497, Priority Dec. 3, 1990, and S.KADLEC, J. MUSIL, Patent CS4804/89, Priority Aug. 14, 1989; and W. D.MÜNZ, F. J. M. HAUZER, B. J. A. BUIL, D. SCHULZE, R. TIETEMA, Patent DE4017111 Priority May 28, 1990]. All described methods have had alimitation in the maximum chamber size, generally limited to 0.5 to 1meters in diameter, that can be used for the deposition of a successfulcoating.

[0005] The present invention overcomes such a limitation and can giverise to a novel apparatus which could be up to four meters in diameter.

DISCLOSURE OF THE INVENTION

[0006] According to one aspect of the present invention there isprovided a vapour deposition coating apparatus comprising a vacuumchamber (1), at least one coating means or ionization source (3)disposed at or about the periphery of a coating zone (2), characterisedin that the apparatus is provided with one or more internal magneticmeans (6) positioned such that magnetic field lines (7) are generatedacross the coating zone (2) and means for altering the strength orposition of the magnetic field lines.

[0007] According to a further aspect of the present invention there isprovided a multi-station deposition unit comprising a plurality ofcoating stations (3,6) each defining a confinement volume, the unitcomprising a plurality of coating means or ionization sources (3)disposed at or about the periphery of the coating zone and one or moreinternal magnetic means (6) (10) positioned such that magnetic fieldlines (7) are generated across each coating zone (2) and means foraltering the strength or position of the magnetic field lines.

[0008] According to yet a further aspect of the present invention thereis provided

[0009] a vapour deposition coating method characterised in that magneticfield lines (7) can be regulated across a coating zone (2) by means (3)(6) which enable an ion current density to be controlled.

[0010] The apparatus can incorporate a number of coating means of whichone is preferably a magnetron cathode which will be situated around thesamples to be coated. At or towards the interior of the chamber a singleor plurality of means generate a magnetic field. These means couldcomprise a single or plurality of magnetic polarities which could be thesame or different to those of the outer magnetic array of the magnetronsource. These magnetic sources provide a means enabling deposition underdifferent ion bombardment conditions to be controlled in different areasof the coating apparatus and/or at different times in the depositionprocess.

[0011] The magnetic strength of these poles could be controlled bydifferent means, e.g. by changing the current of the electromagnet unitsor by mechanical displacement of the permanent magnetic means or both.

[0012] Identical or different magnetron polarities could be used withinthe same apparatus.

[0013] The magnetic strength of the magnetrons could be also varied ascould the relative position of the inner and outer magnetic poles.

[0014] Auxiliary magnetic poles could be used in the chambersurroundings in order to optimise the plasma confinement. Magneticconfinement enhancement could be achieved by magnetic means whichpresent opposite polarity to the central pole. Also suitable electriccurrents could provide adequate magnetic confinement by generatingmagnetic fields for this purpose, especially when they are combined withother magnetic means.

[0015] All these magnetic variations make the apparatus versatile in itsapplications.

[0016] Generally, the apparatus will enable maximum magnetic confinementnecessary in larger deposition apparatus to ensure high qualitycoatings. The internal magnetic means could have independent biasingfrom the samples to be coated. The samples to be coated could be biasedor un-biased. The bias applied to the samples to be coated could bepowered by direct current (DC) and alternative excitation means atdifferent frequencies such as alternating current (AC) at very lowfrequencies (1-1000 Hz), or pulsed voltages at low frequencies(Pulsed-LF) (1-1000 KHz), or medium frequency (MF) waves (1-3 MHz),orradiofrequencies (RF) waves (1-1000 MHz), or any combination ormodulation of these or other excitation means.

[0017] The apparatus could incorporate any other number of means inorder to enhance the ionisation such as microwaves and/or medium andhigh frequency devices and means suitable for the generation of glowdischarges and ion vacuum techniques such as arcs, hot filament, lasers,electron guns and ion beams.

[0018] Larger apparatus, above two meters in diameter can be produced bymagnetic linkage between magnetrons and internal poles. Spatialdistribution of magnetrons and additional magnetic means could be variedin order to achieve optimisation of spaces where magnetic confinementconditions are appropriate for coating depositions. A large coatingapparatus could comprise of one or more confinement areas or stations.

[0019] Various aspects of the invention will be described, by way ofexample only with reference to FIGS. 1 to 11 below in which:

[0020]FIG. 1 shows an example of a deposition apparatus which includesthe basic magnetic confinement described by the present invention;

[0021]FIG. 2 illustrates a three-dimensional view of a depositionchamber described by the present invention;

[0022]FIG. 3 illustrates a deposition unit described by the presentinvention which has additional magnetic means;

[0023]FIG. 4 illustrates a deposition unit with additional magneticmeans which could modulate the magnetic confinement as described by thepresent invention;

[0024]FIG. 5 illustrates a cross section of a deposition unit withindependent biasing for the central magnetic mean from the samples asdescribed by the present invention;

[0025]FIG. 6 shows a multi-station deposition unit described by thepresent invention;

[0026]FIG. 7 represents a multi-station deposition unit described by thepresent invention;

[0027]FIG. 8 illustrates a system with higher levels of magneticconfinement made by retracting to some degree the inner magnetronmagnetic pole as described by the present invention;

[0028]FIG. 9 illustrates a system with low levels of magneticconfinement brought about by the switching of the central polarity suchthat it is the same as the outer pole of the magnetron as described bythe present invention;

[0029]FIG. 10 illustrates a system with very low levels of magneticconfinement which are further decreased by withdrawing the magnetronsouter magnetic pole to some degree as described by the presentinvention; and

[0030]FIG. 11 illustrates a system with different levels of magneticconfinement for different areas of the coating station as described bythe present invention.

[0031] Referring to the figures in turn:

[0032]FIG. 1 represents the top view of a cylindrically shaped chamber.The deposition unit includes a vacuum chamber 1, which is evacuated bymeans of a pumping system. The elements due for coating 2 could rotateso they could face the different magnetrons 3 or other possible coatingmeans or ionisation sources. The sputtering process takes place on thesurface of the magnetron targets 4. The front face of the outer magneticpole of the magnetrons 5 have opposite polarity to the magnetic meansplaced at the central zone of the chamber 6 so that the magnetic fieldlines 7 cross the zone of elements due for coating 2. The magnetic polescontained within the magnetron may or may not have one or severalferromagnetic elements, such as a soft iron backing plate, at the rearof the magnetic pole. The vacuum chamber 1, could be constructed fromnon-ferromagnetic or ferromagnetic material in order to either affect ornot affect the magnetic circuits.

[0033]FIG. 2 represents a deposition apparatus where the magnetrons 3are placed on the chamber wall 1. A magnetic assembly 6 is placed withina central pole. Samples 2 are coated with the target material 4 or anyother chemical compounds formed in plasma reactions during thedeposition process.

[0034]FIG. 3 represents a top view of a two magnetron apparatus wherethe central magnetic means 6 has an opposite magnetic polarity to thatof the outer magnetic means 5 of the magnetrons 3. Additional magneticmeans 8 situated around the samples, e.g. by the chamber walls, providemagnetic fields which complement and enhance magnetic confinement withinthe system so magnetic field lines 7 cross the samples 2 towards thecentral pole.

[0035]FIG. 4 represents a top view of a three magnetron apparatus wherethe central magnetic means 6 has an opposite polarity to that of theouter magnetic means 5 of the magnetrons 3. Additional magnetic means 8and 9 enhance confinement. Magnetic means 6 and 9 could be varied eitherby mechanical displacement or electronic currents so that the degree ofconfinement could be modulated as magnetic lines 7 are altered.

[0036]FIG. 5 represents a cross sectional view of a deposition apparatuswhere the central magnetic means 6 could be independently biased fromthe samples 2. This magnetic array could be left at a floating potential(where electronic current is equal to the ionic current), or biased atthe same or a different potential to that of the samples with a positiveor negative polarity. The samples could be biased by for example DC, AC,Pulsed-LF, MF, RF or any combination or modulation of the above.

[0037]FIG. 6 represents a multi-station coating apparatus where thedeposition units comprise four different coating stations which providefour different confinement volumes. Each station, in the presentexample, has different magnetrons 3 and coats different samples 2.Magnetic confinement is produced between magnetrons 3 and a localcentral pole 6.

[0038]FIG. 7 represents a multi-station coating apparatus. Thedeposition apparatus comprises three different sample holders 2. In thepresent example all the magnetrons are situated on the chambers wall 1.Two series of magnetic poles 6 and 10 of opposite polarity direct themagnetic field lines 7 across the samples.

[0039]FIG. 8 represents a single station coating apparatus with themagnetrons inner magnetic means 11 being withdrawn independently of themagnetrons outer magnetic means 5 so as to further enhance the magneticlinkage 7 to the central pole 6 and the magnetrons outer magnetic means5. Central magnetic means 6, as an example, comprises a number ofindependently controlable magnetic means 12 each of which canindependently have its polarity changed by for example rotation and/ortranslation of their constitutive permanent magnets.

[0040]FIG. 9 represents a single station apparatus where the centralmagnetic means 12 have been reversed such that the polarity is the sameas the magnetrons outer magnetic means 5, hence having the effect ofpreventing linkage with the inner magnetic pole 6.

[0041]FIG. 10 represents a single station coating apparatus where thecentral magnetic means 12 have been reversed such that the polarity isthe same as the magnetrons outer magnetic means 5, with the furtherretraction of the magnetrons outer magnetic means 5 increasing theeffect of preventing linkage with the inner magnetic pole 6.

[0042]FIG. 11 represents a single station coating apparatus where thecentral magnetic means 12 have two different polarities. At the sametime the magnetrons have two different polarities 3 a and 3 b, providingdifferent magnetic confinement in different areas of the station. Thissituation allows coating deposition at different degrees of ionbombardment. Targets 4 could be of the same or of different materials.In the present example three of the magnetrons present a magneticconfinement due to complementary polarity with the central magneticmeans. One of the magnetrons presents the same polarity as thecorresponding central magnetic mean preventing linkage with the innermagnetic pole 6.

1. A Vapour deposition coating apparatus comprising a vacuum chamber(1), at least two magnetons (3) disposed at or about the periphery ofone side of a coating zone (2) and at least one magnetic means (6)disposed at or about the periphery of the other side of the coating zonesuch that it is common to and magnetically links at least two of said atleast two magnetons to generate magnetic field lines (7) from one sideof the coating zone (2) to the other, said apparatus further comprisingmeans for altering the strength or position of the magnetic field lines.2. An apparatus as claimed in claim 1 in which the coating zone isannular.
 3. An apparatus as claimed in claim 1 or 2 in which themagnetic means (6) in a permanent magnet.
 4. An apparatus as claimed inany of the preceding claims in which the at least one magnetic means ispositioned substantially at the centre of the chamber.
 5. An apparatusas claimed in any of the preceding claims wherein the at least onemagnetic means (6) comprises a single or plurality of polarities facingthe coating zone.
 6. An apparatus as claimed in any of the precedingclaims, comprising means for displacing the at least one magnetic means(6)
 7. An apparatus as claimed in any of the preceding claims in whichthe magnetrons (3) and/or the at least one magnetic means (6) havedifferent polarities and are arranged such that the polarities can bealtered with respect to one another.
 8. An apparatus as claimed in anyof the preceding claims wherein the at least one magnetic means (6) isrotatable.
 9. An apparatus as claimed in any of the preceding claimswherein the at least one magnetic means (6) is independently biased fromsamples to be coated in the coating zone.
 10. An apparatus as claimed inany of the preceding claims wherein the at least two magnetons comprisean inner magnetic means (11) of one polarity and outer magnetic means(5) of an other polarity.
 11. An apparatus as claimed in claim 10wherein the inner magnetic means can be withdrawn independently of themagnetons outer magnetic means or vice versa.
 12. An apparatus asclaimed in any of the preceding claims wherein the at least one magneticmeans (6) comprises a number of independently controllable magneticmeans (12) each of which can independently have its polarity changed.13. An apparatus as claimed in claim 12 wherein the independentlycontrolable magnetic means (12) are rotatable.
 14. An apparatus asclaimed in any of the preceding claims further comprising additionalmagnetic means (8) disposed between the magnetrons about the peripheryof the oneside of the coating zone.
 15. A multi-station vapourdeposition apparatus comprising a plurality of coating zones (2) eachdefining a confinement volume the apparatus comprising a vacuum chamber(1), at least two magnetons (3) disposed at or about the periphery ofone side of each coating zone and at least one magnetic means (6)disposed at or about the periphery of the other side of each coatingzone such that it is common to and magnetically links at least two ofsaid at least two magnetons to generate magnetic field lines (7) fromone side of each coating zone to the other, said apparatus furthercomprising means for altering the strength or position of the magneticfield lines.
 16. An apparatus as claimed in claim 15 comprising twoseries of magnetic poles (6) and (10) of opposite polarity to direct themagnetic field lines (7) across each coating zone.
 17. An apparatus asclaimed in claim 15 comprising a further magnetic meas 10 whichmagnetically links each coating zone to one another.
 18. A vapourdeposition coating method characterised in that magnetic field line (7)are regulated across a to coating zone (2) of an apparatus as claimed inany of the preceding claims by altering their strength or position.